Has the UK spoken out?

Since the start of the Yemen war, Britain has licensed at least $4.7 billion of arms to Saudi Arabia, which is leading a coalition fight against Houthi rebels in the region.

In a statement, Foreign Secretary Jeremy Hunt said he would “treat the incident seriously” and stressed friendships that “depend on shared values” between the UK and Saudi Arabia.

A joint statement between Britain, France and Germany called for a “credible investigation”, with Hunt adding that if Saudi Arabia was behind the disappearance, Britain would “have to think about the appropriate way to react in that situation”.

What has been the international reaction?

Mixed. On Tuesday, US Secretary of State Mike Pompeo flew to Riyadh and thanked King Salman for his “commitment to supporting a thorough, transparent, and timely investigation” into Khashoggi’s disappearance, a spokeswoman said.

It follows suggestions by US President Donald Trump that “rogue killers” may have been responsible for Khashoggi’s alleged murder.

After a phonecall with King Salman on Monday, Trump said: “The king firmly denied any knowledge of it”.

She called for Riyadh to waive immunity on its diplomatic premises and officials.

“Under international law, both a forced disappearance and an extra-judicial killing are very serious crimes, and immunity should not be used to impede investigations into what happened and who is responsible,” she said.

Ahead of a business summit in Saudi Arabia on October 23, a number of high profile banking and business leaders have pulled out, including the chief executives of HSBC, Credit Suisse and Standard Chartered.

Google also pulled out this week.

The disappearance has hit the Saudi economy with the stock market falling 7% on Sunday.